﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace DyUi.Interfaces
{
    public static class UiHelper
    {
        public static IEnumerable<T> FindLogicalChildren<T>(this DependencyObject parent) where T : DependencyObject
        {
            List<T> list = new List<T>();

            Action<DependencyObject> getCildren = null;
            getCildren =
                (parentInternal) =>
                {
                    LogicalTreeHelper
                    .GetChildren(parentInternal)
                    .Cast<DependencyObject>()
                    .ToList()
                    .ForEach
                    (
                        a =>
                        {
                            if (a is T) list.Add(a as T);
                            getCildren(a);
                        }
                    );
                };

            if (parent != null) 
            {
                getCildren(parent);
            }
            return list;
        }

        public static IEnumerable<T> FindVisualChildren<T>(this DependencyObject parent) where T : DependencyObject
        {
            if (parent != null)
            {
                for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
                {
                    DependencyObject child = VisualTreeHelper.GetChild(parent, i);
                    if (child != null && child is T)
                    {
                        yield return (T)child;
                    }

                    foreach (T childOfChild in FindVisualChildren<T>(child))
                    {
                        yield return childOfChild;
                    }
                }
            }
        }

        /// <summary>
        /// Finds a Child of a given item in the visual tree. 
        /// </summary>
        /// <param name="parent">A direct parent of the queried item.</param>
        /// <typeparam name="T">The type of the queried item.</typeparam>
        /// <param name="childName">x:Name or Name of child. </param>
        /// <returns>The first parent item that matches the submitted type parameter. 
        /// If not matching item can be found, a null parent is being returned.</returns>
        public static T FindChild<T>(this DependencyObject parent, string childName) where T : DependencyObject
        {
            // Confirm parent and childName are valid. 
            if (parent == null) return null;

            T foundChild = null;

            int childrenCount = VisualTreeHelper.GetChildrenCount(parent);
            for (int i = 0; i < childrenCount; i++)
            {
                var child = VisualTreeHelper.GetChild(parent, i);
                // If the child is not of the request child type child
                T childType = child as T;
                if (childType == null)
                {
                    // recursively drill down the tree
                    foundChild = FindChild<T>(child, childName);

                    // If the child is found, break so we do not overwrite the found child. 
                    if (foundChild != null) break;
                }
                else if (!string.IsNullOrEmpty(childName))
                {
                    var frameworkElement = child as FrameworkElement;
                    // If the child's name is set for search
                    if (frameworkElement != null && frameworkElement.Name == childName)
                    {
                        // if the child's name is of the request name
                        foundChild = (T)child;
                        break;
                    }
                }
                else
                {
                    // child element found.
                    foundChild = (T)child;
                    break;
                }
            }

            return foundChild;
        }

    }

}
